Transfer copy process and material

ABSTRACT

AN UPPER SHEET AND A LOWER SHEET, ADAPTED TO BE SUPERIMPOSED TO FORM AN INTERFACE BETWEEN THE SHEETS, ARE COATED ON SAID INTERFACE WITH RESPECTIVE INGREDIENTS FOR A HEATINDUCED, COLOR-PRODUCING CHEMICAL REACTION. THE TRANSFER LAYER HAS A SYNTHETIC-RESIN BODY WHILE THE RECEPTOR LAYER HAS A WAX BASE WITH A SOFTENING POINT BELOW THE ACTIVATION TEMPERATURE OF THE REACTION.

Jan. 29, 1974 w. SCHUTZNER 3,788,875

TRANSFER COPY PROCESS AND MATERIAL FIG! Filed July 15, 1971 "all; I; QM 22 'I'II'IIIIII/IIIIIII 2/ 'y'fi 20 23 m\\\\\\\\\l 'IIIIIIA United States Patent O 3,788,875 TRANSFER COPY PROCESS AND MATERIAL Walter Schutzner, Vienna, Austria, assignor to W. Koreska, Vienna, Austria Continuation-impart of application Ser. No. 768,346, Oct. 17, 1968, now Patent No. 3,640,750. This application July 16, 1971, Ser. No. 163,482 The portion of the term of the patent subsequent to Feb. 8, 1989, has been disclaimed Int. Cl. B41m 5/22 US. Cl. 11736.2 3 Claims ABSTRACT OF THE DISCLOSURE An upper sheet and a lower sheet, adapted to be superimposed to form an interface between the sheets, are coated on said interface with respective ingredients for a heatinduced, color-producing chemical reaction. The transfer layer has a synthetic-resin body while the receptor layer has a wax base with a softening point below the activation temperature of the reaction.

CROSS-REFERENCE TO COPENDING APPLICATION This application is a continuation-in-part of my copending application Ser. No. 768,346 filed Oct. 17, 1968, now US. Pat. 3,640,750 issued Feb. 8, 1972.

FIELD OF THE INVENTION This invention relates to a process of making copies by color-producing chemical reactions. More particularly, the invention is concerned with a novel transfer copy system.

BACKGROUND OF THE INVENTION Various processes of making multiple records without interleaved carbon paper have already been proposed. One class of such processes is based on the transfer of carbon. The sheet which is Written upon is provided on the rear with a coating which produces marks on an underlying sheet of paper under the action of writing pressure.

Such carbon layers render the handling of the papers more difficult and tend to soil the hands and the backing surface. It is also difficult to avoid the making of undesired copies. In view of these disadvantages of carboncoated papers, color-transferring coatings have been designed, which enable a transfer under pressure in cooperation with special receiving layers only, which in most cases contain wax.

In the latter arrangement, the danger of undesired copies was reduced but not entirely eliminated. With increasing use of this copying process in a typing office, there will arise an increasing probability of a color-transferring layer and a receiving layer becoming superimposed so that undesired color transfer can result.

Another class of processes is based on color-producing chemical reactions.

In the latter processes, the production of undesired copies is avoided in that each sheet is provided on its rear with an inherently colorless substance giving a color-producing chemical reaction upon contact with a second colorless substance selected to react with the first substance. The second substance is provided as a coating on the face of the succeeding sheet.

Under the writing pressure, part of the first substance is transferred to the copy sheet where it contacts the second substance so that the reaction takes place immediately.

The use of this system also results in an undesired transfer of color if two corresponding sheets for use in the same transfer copy process become accidentally superimposed in a filing tray. Besides, such sets of writing papers 3,788,875 Patented Jan. 29, 1974 ice do not have a long shelf life because the color-producing reaction may even be caused under the pressure due to the weight of the paper itself.

OBJECTS OF THE INVENTION SUMMARY OF THE INVENTION These objects and others which will become apparent hereinafter, are attained with a method of transferring an image to a receptor layer from a transfer layer wherein each of these layers contains at least one reagent capable of chemical interaction with the reagent of the other layer upon heating to a temperature above ambient but so selected as to form a latent image by pressure transfer in the receptor layer which is uncolored. An essential feature of the invention is the fact that the transfer layer is caable of selectively applying its reactive component to the receptor layer in a manner which necessitates heating to permit the reaction to be carried out.

More specifically, the system of the present invention comprises a two-layer system in which, for example, a receptor layer is applied to the obverse side of a copy sheet and a transfer layer to the reverse side, the transfer layer having a synthetic-resin binder in which one of the color-producing reagents is received.

While transfer papers have been provided heretofore in such manner that the receptor layer must be a wax or other substance selectively designed to receive the transfer, the provision of waxes in the transfer layer effectively permits transfer to any hydrophobic surface and, when a surface is warm or a slight pressure is applied, to any surface at all.

In practice, the mere contact of wax-containing transfer layers with wax-containing receptor layers is sufiicient to cause a limited transfer of the coloring material even in the absence of intended transfer pressures. As a result, thermal development of the intended image develops the smudge as well. I have found, and it is an important feature of the invention, that this disadavntage can be obviated by substituting for wax-containing transfer layers, in heat-activated, two-reagent systems in which the receptor layer contains a wax, a synthetic-resin binder for the transfer layer. Not every binder has been found to be effective for my purposes and I wish to mention specifically ethylcellulose, vinylchloride-vinylacetate copolymers and such systems which are without polyethylene, which appear to have the characteristic necessary for the present invention. This characteristic is a particulate distribution of the reagent, binder and any pigmenting or masking material in the transfer layer such that the transfer is effected in the form of grains. This does not occur when wax-containing transfer layers are employed.

I have found, furthermore, that not all reactive materials capable of producing colored reaction products upon heating can be used effectively. In this connection, I should observe that the color must be permanent and nonfading, must be concentrated at the points of latent image impression transfer and be free of a tendency to diffuse upon heating and should be free from the tendency to develop where only light or smudge pressures transfer the reagent. These results are obtained 'by reaction systems in which one of the reactants is a heavy-metal salt of a longchain fatty acid, especially stearic acid and best results are obtained with ferric stearate, copper(II) stearate, nickel stearate, cobalt stearate and the equivalent heavymetal salts of other fatty acids having, for example, to 30 carbon atoms in the carbon chain. More generally, the heavy-metal soaps of the fatty acids should be those which form deeply-colored compounds upon reaction with another reagent in the presence of heat.

The other reagent according to the present invention is preferably an amine salt of dithiocarbamatic acid such as piperadine, N,N-pentamethylenedithicarbamate, and alkylgallate. Specific compounds which have been found to be most effective are methyl and dodecylgallate, zinc dibutyldithiocarbamate, zinc diethyldithiocarbamate and zinc dibenzyldithiocarbamate, malachite-green lactone and CHs-C CHr-C The color reagent may be present in an amount ranging from 2 to 35 percent by weight of the layer while the heavy-metal salt of the fatty acid should be present in an amount ranging between 0.5 and 30 percent by weight of the respective layer, either reagent being present in either the transfer or the receptor layer.

The process according to the invention is thus mainly characterized in that at least one of the ingredients required for the reaction is transferred under the action of the writing pressure to a copy sheet, where it is contacted with any other ingredients which may be required for such reaction, and the reaction is subsequently effected by heating.

In one embodiment of the invention, a copying material is utilized consisting of at least two superimposed sheets. At least one of the ingredients required for the color-producing reaction is contained in a coating provided on the underside of the upper sheet and adapted to be transferred by local pressure onto the underlying sheet. That coating preferably contains a film-forming binder, desirably having a loosened, particulate structure. Such structure may be obtained, e.g. by incorporation of waxes or waxlike substances.

In a particularly preferred embodiment of the invention, the lower sheet is provided on its upper surface with a receiving coating containing a waxlike binder and, if required, one or more of the other ingredients required for the reaction.

Alternatively, all ingredients required for the colorproducing reaction may be incorporated in the transferable coating. In this case, it is sufiicient to provide a receiving coating which contains a waxlike binder only, which upon a temperature rise acts as a solvent for at least one of the two ingredients.

It is also possible to provide a cover layer over the transferable coating, the cover layer consisting preferably of waxlike substances, similar to the receiving coating previously mentioned, and which causes the particles detaching from the transferable coating under the action of the writing pressure to adhere to ordinary paper.

The waxlike substances in the covering or in the receiving coating are preferably selected to melt at a temperature in the range of 60-150 C.

In a special embodiment of the invention, the waxlike substance may be one of the reactants, e.g. a heavy metal soap.

It is apparent from the above that the formation of undesired copies may be prevented not only by choice of the ingredients required for the reaction similar to the known process outlined above, but also by the fact that the writing remains invisible unless the copy sheet is heattreated. Such heat treatment is not likely to be applied accidentally to filed letters so that a formation of undesired copies can be entirely prevented.

When two or more sheets according to the invention are superimposed in a copying set, the uppermost sheet should have a coating on the underside only and the lowermost sheet on the upper side only whereas the intermediate sheets are provided with coatings on both sides.

SPECIFIC EXAMPLES Example 1 The following ingredients were jointly ground in a ball mill:

Parts by weight Vinylite VYHH-1 (a polyvinylchloride-acetate copolymer) 5 Kaolin 45 Methyl gallate 30 Acetone 200 Parts by weight Ozocerite wax 10 Ferric stearate 2 The mixture is fused and applied to the paper as a coating having a weight of 2-3 grams per square meter.

When two papers thus coated are superimposed in such a manner that the rear side of the first-mentioned sheet lies adjacent to the forward side of the second sheet, the application of pressure, e.g. by the impact of a type or by a pencil or ball point pen, will cause parts of the transferable coating along the trace to be transferred to the receiving coating where the transferred matter remains invisible initially. If the copy sheet is subjected to a heat treatment, e.g., in a drying cabinet adjusted to a temperature of C., a black writing will be produced. Instead of being heated in a drying cabinet, the sheet may be heated by means of a heated roll, a hotplate or a flatiron. Alternatively, the writing may be developed by infrared radiation or by a hot-air stream. It is essential, however, that the heating is suflicient to melt at least one ingredient, in the present case the mixture of ozocerite and ferric stearate so that the reaction with the methyl .gallate is initiated at those portions which correspond to the writing.

[Example 2 To the paper substrate of Example 1, a transfer coating is applied to the reverse side in an amount of 5 to 6 g./m. this coating consisting of:

Dodecylgallate 1 To the obverse side was applied a 2 to 3 g./m.= of a. receptor layer consisting of:

Parts by weight Ceresine wax 10 Cobalt stearate 2 Example 3 A writing paper is provided on its rear side with a transferable coating having the following composition:

Parts by weight Vinylite VYHH-l 5 Kaolin 45 Zinc dibutyldithiocarbamate 10 Acetone I 200 A receiving coating consisting of ozocerite (10 parts by weight) and ferric stearate (2 parts by weight) is applied to the forward side of the sheet, the coating 5 having a weight of 2-3 grams per square meter. A brownish black writing is obtained under the conditions stated in Example 1.

1 Example 4 -A one-layer transfer system is made using the composition of Example 3 except that the ferric stearate is omitted from the receiving layer and 20 parts by weight of ferric stearate is incorporated in the transfer layer.

Example 5 The system of Example 3 is used except that 10 parts by weight of copper(II) stearate is substituted for the ferric stearate.

Example 6 The system of Example 3 is used except that 10 parts by weight of cobalt stearate is substituted for the ferric stearate in the receiving layer.

Examples 7a-7c equivalent results.

Examples 921-90 The system of Examples 3, 5 and 6 were followed except that 10 parts by weight of:

was substituted for the zinc dibutyldithiocarbamate with equivalent results.

Example 10 The transfer layer of Example 3 was used. The receiving layer was constituted as a mixture of:

Parts by weight 1 Opanol B 150 C0pper(II) stearate Gasoline (vaporizable solvent) 80 The receiving layer was applied to the paper substrate and the solvent evaporated. As in Example 3, thermal development produced a black image. The receiving layer has a bluish-green coloration as compared to the light-beige coloration of Example 4.

Example 11 The transfer layer applied to the substrate consists of: Parts by weight Zinc dibutyldithiocarbamate 30 Ozocerite 50 Kaolin The composition is melted and applied to the reverse side of the substrate while the obverse side is coated with a receptor layer consisting of:

Parts by weight Vinylite VYHHI 5 Ferric stearate 10 Titanium dioxide 10 Acetone 75 The composition dispersed in the acetone is applied to the surface of the substrate and the acetone permitted to evaporate. When used as a transfer paper in Example 3, a black image is produced.

Examples 12a-12c For the zinc dibutyldithiocarbamate of Example 12, each of the following are substituted in equivalent portions by weight and with similar results:.

zinc diethyldithiocarbamate zinc dibenzyldithiocarbamate and un-org: s oH.-orn cm N-fiitN orn CHI-C142 x- 2 Examples 13a-13b With each of the systems of Examples 11 and 12a12c, equivalent quantities of copper stearate, nickel stearate and cobalt stearate were substituted for the iron stearate with similar results.

DESCRIPTION OF THE DRAWING SPECIFIC DESCRIPTION FIG. 1 shows a top sheet 10, an intermediate sheet 20 and a bottom sheet 30. It will be apparent that the top sheet 10 and the bottom sheet 30 are upper and lower sheets, respectively, with respect to the intermediate sheet 20, and that the latter is a lower sheet with respect to the top sheet 10 and an upper sheet with respect to the bottom sheet 30.

The top sheet 10 has a backing layer 11 of paper and a transferable coating 12 facing the intermediate sheet 20. The intermediate sheet 20 has a core layer 21 of paper, a receiving coating 22 facing the coating 12 and a transferable coating 23 facing the bottom sheet 30. The bottom sheet 30 has a backing layer 31 of paper and a receiving coating 32 facing the transferable coating 23.

The transferable coatings 12 and 23 and the receiving coatings 22 and 32 may be composed as described in the specific examples.

FIG. 2 shOWS a top sheet 40, an intermediate sheet 50, and a bottom sheet 60. It will be apparent that the top sheet 40 and the bottom sheet 60 are upper and lower sheets, respectively, with respect to the intermediate sheet 50, and that the latter is a lower sheet with respect to the top sheet 40 and an upper sheet with respect to the bottom sheet 30.

The top sheet 40 has a backing layer 41 of paper and a transferable coating 42 facing the intermediate sheet 40. The intermediate sheet 50 has a core layer 51 of paper, a receiving coating 52 facing the coating 42 and a transferable coating 53 facing the bottom sheet 60. The bottom sheet 60 has a core layer 61 of paper and a receiving coating 62 facing the coating 53.

The transferable coatings 42 and 53 and the receiving coatings 52 and 62 may be composed as described for such coatings in Examples 8 and 10.

FIG. 3 shows an upper sheet 70 and a lower sheet 80. The upper sheet 70 has a backing layer 71 of paper and a transferable coating 72, which is covered by a coating 73 of wax or wax-like material, e.g., as described in Example 9. The lower sheet consists on its surface facing the coating 73 of a material to which the material of the coating 73 can adhere. The transferable coating 72 may be composed as described for such coating in Examples 8 and 10.

I claim:

1. A method of producing an image comprising the steps of disposing a transfer layer of a first flexible substrate in surface-to-surface contact with a receiving layer of another substrate, said transfer layer comprising a first color-producing component and a binder selected from the group which consists of ethyl cellulose and vinylchloridevinylacetate polymers bonding same to said first substrate in granular form for substantially colorless transfer to said second substrate upon application of pressure to said first substrate, said receiving layer comprising a second color-producing component reactive under the application of heat at a temperature of 60 C. to 150 C. with said first component to produce a visible reproduction of a latent image formed by pressure transfer of said first component onto said second substrate, and a binder for said second component; applying pressure to said first substrate to transfer said first component to said second substrate and form a latent image thereon; and heating said second substrate to said temperature to react said components and develop said latent image, one of said components being a heavy-metal salt selected from the group which consists of ferric stearate, nickel stearate, cobalt stearate and copper stearate, the other of said components being selected from the group which consists of zinc dialkyl and diaryldithiocarbamates, piperidines, alkyl gallates and CH -CH s CH CH i H) T- 7 CH1 N- -s HN CH1 CHr-CHz CH3-CH1 2. A multiple-copy paper comprising a flexible substrate having a pair of opposite surfaces; a first layer coated onto one of said surfaces and consisting of a composition transferable under pressure substantially only to a waxy coating and composed essentially of a binder, pigmentatious or filler material, and at least one thermally activatable Clfl N--S HN CH:

CH CK; CHr-CH the other of said compounds being a heavy-metal salt of a fatty acid selected from the group which consists of ferric stearate, nickel stearate, cobalt stearate and copper stearate.

3. The copy paper defined in claim 2 wherein said receiving layer includes ozocerite or ceresine wax.

CHr-CH;

References Cited UNITED STATES PATENTS 3,640,750 2/1972 Schutzner 117-363 MURRAY KATZ, Primary Examiner US. Cl. X.R.

1l7l.7, 36.3, 36.4, 155 UA; 26041 C 

